Drill collar and method of making the same



Aug. 3 1926.

. E. TIMBS ET AL DRILL COLLAR AND METHOD OF MAKING THE SAME gnomfloz, J @1711: (co 0 C artoznu gx w a w m w u 4 5 0 z m T a??? f d Patented Aug. 3, 1926.

f "1,594,579" UNITED, STATES PATENT I o F cE'. I

EDWARD 'IIMBS, or LOS- ANGELES, AND enonen. D. wnrson, or 'ronmcn, enm- FORNIA, ASSIGNORS TO UNION TOOL. COMPANY, OF TORRANCE, CALIFORNIA, A.

CORPORATION OF CALIFORNIA.

DRILL comm AND METHOD or MAKING r1111; SAME.

Application filed Apri1 15, 1925. Serial No. 23,402.

This invention relates to drill collars such as are used to connect a rotary tool string to a drill bit when drilling a well. A drill bit is subjected to very severe strains while cutting its way through a'rock stratum, and these strains are transmitted from the bit to the tool string through the drill collar. Many breakages of drill collars occur by reason of their lack of flexibility. As usually constructed in practice, these drill col lars are relatively expensive to manufacture and they, have also an undesirable rigidity.

The general object of the invention is to produce a drill bit having a' high degree of flexibility with suflicient strength to impart the torsion forces from the drill bit to the tool string, so constructed as to enable it to be very economically produced. The inven- I 0' tion includes the method of constructing the 'drill collar as well as the drill collar itself.

Further objects of the invention will appear hereinafter. As regards the tion consists in the novel parts and combinascale.

tion of parts to be described hereinafter, all of which contribute to produce an efficient drill collar; as regards the method of constructing the drill collar, the invention consists in those novel steps and. combination of steps to be described hereinafter.

Aprefered embodiment of the invention is described in the following specification, while the broad scope of the invention is pointed out in the appended claims In. the drawing drill collar itself,the inv en- Fig. 1 is a side elevation of a drill bit ein-i bodying our invention, the middle portion of the same being broken away. and the lower portion being shown partially in section; Fig. 2 is a fragmentary longitudinal section taken through the wall of the upper head and illustrating its connection to the body of the drill collar. This view is upon an enlarged scaleQ Fig. 3 is a horizontal cross section taken on the line 3-3 of Fig. 1, but upon a larger Fig. 4 is a side elevatidfi and partial section, bro lgen away, and illustrating another v embodiment of the invention.

- In practicing our methodyweproduce' a built-up drill collar havinga body comprising an inner tube with an outer tube surroundv a ing it. On the intermediate portion of the body, the walls of these telescoped tubes are disposed apart so that there is an annular space between them, but the wall of the drill collar is constructedso that the walls of the tubes come together, at each end of the drill collar, at which points we attach the heads to the body. The walls" of the tubes are rigidly connected together. .The connections of the body to the heads may be made in any desired manner.

We shall now describe a preferred construction for producing this built-up drill collar, referring especially to Figs. 1 to 3. I

The body 1 of the drill collar, as indicated above, is composed of an inner tube 2 andan outer tube 3; one end of the inner tube, for example the upper end, is attached to a head 4. In order to attach the head, we prefer to provide a tapered screw connection 5 which enables the inner tube to be screwed into the lower end of the head 4:. We prefer also to provide a reinforced or thickened wall 6 for the inner tube in the vicinity of the screw connection and extending a short distance below the lower end 7 of the head 4.

After the inner tube has been attached in this way we slip over it the outer tube 3 which telescopes with the inner tube as indicated, an we then attach the adjacent end of the outer 'tube to the inner tube. We also secure the end of the outer tube to the lower endor adjacent end of the head 4.

v 11 order to accomplish this and at the same time to form an annular space 8 between the inner tube and outer tube, we prefer toplace a'spacer ring 9 between the walls of the tubes and adjacent to the head i (see Fig. 2). This spacerring substantially fills the annular space 8. .We then spot-weld the inner tube and outer tube together at the spacer ring 9. V 1

In order to increase the strength in forming the weld, we form it so that there is virtually a key-connection formed through theconnected walls. This is accomplished by drilling atapered socket 10 through the wall of the outer tube 3 and through the,;.,

- The result "of this is that the metal of the key or plug 11 is burned in or fused into the metal of the, adjacent parts, forming an integral part of the walls which are in contact with this plug or key.

We also prefer to produce a butt-weld 12 between the adjacent end of the outer tube and the head, as indicated.

The upper end of the head4 is provided with means such as a boss with a thread 13 to which a tapered pin at the lower end of the drill string may be attached.

After attaching the inner and outer tubes to the upper head, we attach the lower head to these tubes in any suitable manner. We prefer, however, to provide screw-threads 14 on the. lower end of the inner tube similar to the threads which occur at the screw connection 5. By means of these threads 14 we attachthe lower end of the inner tube to the other head 15. The outer tube 3 should be of suflicient length so that its other end will be adjacent to the upper end 16 of the lower head;

.When head 15 isscrewed into place, a distance ring similar to the distance ring 9 is placed over the adjacent end of the inner tubeand a welded connection is formed at this point, and this connection is preferably made in the same manner as at'the other end of the body in connecting the inner tube and outer tube together. The adjacent end of the head 15 is also preferably connected by a butt-weld 17 to the adjacent end of the outer tube 3.

It will-be evident that a drill tube collar constructed as described will have relatively together adjacent the heads so that the torsion forces transmitted through the two wallsof the'body will'be imparted to the head 4 as though the drill collar were made in one piece.

If it is desired to practice the invention.

without the use of welding, this can be done by constructing the drill collar as illustrated in Fi 4. In this instance, the inner tube 18 has a thread connection 19 by means of which it is attached to the upper 4 head 20. The outer tube 21 is telescoped over this inner tube and the walls of the two tubes come together at a seat 22 adjacent the head; below this seat the walls of the tubes separate so as to form an annular space 23 between the tubes.

The outer tube 21 has a screw connection '24 connecting it to the head 20. After the two tubes have been attached to the upper head in this way, the incomplete drill collar is then put in a lathe and a thread 25 chased on the end of the inner tube, which projects beyond the end 26 of the outer tube at the lower end, as shown in Fig. 4. A thread 27 is chased on the outer side'of the outer tube. These threads 25- and 27 have the same pitch and they also start at the same point, that is to say, they start on the same radius from the axis .of the drill collar. The lower head has threads similar to the threads-25 and 27, which also start at points on the same radius line. This enables the lower head to be screwed into place on the threads 25 and 27. The walls of the two tubes 18 and 21 come together at 28 near the lower head, just-as at the point 22.

The lower end of the head 15 is provided with means such as threads 29 for attaching it to the tapered pin of the drill bit.

A drill collar constructed in this way will have very desirable flexibility, but necessitates carefully conducted threading oper-- ations. However, in some situations it may be more feasible to construct a drill collar in this way than by the use of welding, as described in connection with Fig. l.

It is understood that the embodiment of the invention described herein is only one of the many embodiments this invention may take, and we do not wish to be limited in the practice of the invention, nor in the claims, to the particular-embodiment set forth.

' lVhat we claim is 1. A built-up drill collar having a body comprising an inner tube with an outer tube telescoped over the inner tube, and a head at. each end connected to the two tubes, said heads having means for connecting the same respectively to the drill string and the drill bit.

2. A built-up drill collar having a body comprising an inner tube with an outer tube telescoped over the inner tube, and a head at each end connected to the two tubes, said heads having means for connecting the same r'respectively to the drill string and the drill bit, the wall of said drill collar being constructed so that the ivalls of said tubes are rigidly connected together at each end of the drill collar adjacent the heads, said walls having an annular s ace between them at the intermediate portion of the body.

'3. A built-up drill collarhaving a head at each end, and having a body consisting of an inner tube connecting the said heads, with an outer tube surrounding the inner tube and having a weld at its ends connecting it to saidheads.

4. A built-up drill collar having a head at each end, and having a body consisting 0 an inner tube with a thread connection at each end connectin heads, and an outer tu e surrounding the the same to the seated in the walls of the ISO 6. A built-up drill collar havinga: head.

at each end and a body consisting of an inner tube with an outer tube surrounding the innertube', and connected to the heads, and key-connections between the inner tube and the outer tube adjacent each head.

7. A built-up, drill collar having a head at each end and having a body consisting of an inner tube with an outer tubev surrounding the inner tube, the wall of said drill collar being constructed so that the Walls of said tubes come together at each end of the drill collar adjacent the heads, the walls of said tubes having air annular space between them at the intermediate portion of the body, and key-connections between the inner tube and the outer tube adjacent the heads.

8. A built-up drill collar having a head at each end and having a body consisting of an inner'tube with an outer tube surrounding the inner tube, a spacer ring separating the inner tube from the outer tube adjacent the head, and key-connections tubes and the ring. v.

9, A built-up drill collar having a head at each end and having a body consisting of an inner tube with an outer tube surrounding the inner tube, a spacer ring between'thewalls of the tubes adjacent the head and welded to the walls of the tubes,

and keys burnt into the walls of the inner and outer tubeand passing through the spacer ring. I

10. A builtup drill collar having a head at-each end and having a body consisting of an inner tube having a thread connection at each end connecting the same to the heads, LIldi an outer tube surrounding the inner tube and having a weld at its ends connecting the same to theheads, a spacer ring between the walls of the tubes adjacent each head, and connectingikeys burnt into the walls -oftthe tubes and the spacer ring. V V

11,. The method of making a built-up drill collar which consists in attaching an. inner tube to a head, telescoping an outer tube over the inner tube and welding the same to the head, attaching another head to the other end of the inner tube, and welding the same to the other end of the outer tube.

'12. The method of making a built-up drill collar, which consistsin connecting an in- 'ner tube to a head by a screw-connection;

telescoping an outer tube over the inner tube, welding theend of the outer tube" to s the head, attaching another head to the other end of the inner tube, and welding the same to the other end of the outer tube.-

13. The method of making a built-up drill collar, which consists in attaching ahead to an inner tube, placing a spacer ring over the inner tube adjacent the head, telescoping an outer tube over the inner tube with its end over the spacer ring, and welding the walls of the tubes to the spacer ring.

.14. The irrethod of making abuilt-up drill collar, which consists in attaching a head to an inner tube, placinga spacer r1ng over the inner tube adjacent the head, telescoping an outer tube over the inner tube with its end over the spacer .ring, welding the walls of the tubes to the spacer ring, and geltiiling the end of the outer tube to the 15. The method of making a built-up drill,

collar,'which consists in attaching a head to one end of an inner tube, placing a spacer ring over the inner tube adjacent the head, telescoping an outer tube with its end over the spacer ring, forming a socket through ring and extending into the inner tube, and

burning a key into the socket.

Signed at Torrance,

of April, 1925.

EDWARD TIMBS. GEORGE D. WATSON."

. the Wall of the outer tube through the spacer Caliii, this 4th day 

